Brissus gigas H.B. Fell, 1947
This is not a Mollusc. Other non-Molluscan Phyla (Echinodermata, Brachiopoda etc) have been included to help identify species that may be mistaken for Mollusca, but are not.
Echinodermata (Phylum) > Echinozoa (Subphylum) > Echinoidea (Class) > Euechinoidea (Subclass) > Spatangoida (Order) > Brissidae
(Family) > Brissus
(Genus) > gigas (Species)
From 8-200 metres